1. Field of the Invention
This invention relates to a quantum device and its manufacturing method.
2. Description of the Prior Art
Recently, in quantum wave electronics, a quantum microstructure called a quantum box, which has a cross sectional dimension equivalent to the de Broglie wavelength of an electron, is remarked, and the quantum effect exhibited by a zero-dimensional electron confined in the quantum box has become a matter of great concern.
A concept of a coupled quantum boxes device (also called an assembled quantum boxes device) has arisen as a sort of quantum devices using quantum boxes, and a study has started to realize it. Such a coupled quantum boxes device includes quantum boxes arranged so as to cause transition of electrons (e.sup.-) among the quantum boxes, due to quantum mechanical tunneling or other mechanism, to thereby change the distribution of electrons to effect information processing.
In order to realize a coupled quantum boxes device which utilizes tunneling of electrons among quantum boxes, it is necessary to arrange the quantum boxes in near positional relations by a distance less than the order of 10 nm.
Quantum boxes of a size on the order of 10 nm can be made by the electron beam lithography. As to the distance between the quantum boxes, however, the order of 50 nm is the limit because of the proximity effect and scattering of electrons during exposure. With the distance on the order of 50 nm between quantum boxes, the coupling force between the quantum boxes is very weak, and the operation speed of the coupled quantum boxes device is slow.
Such a decrease in operation speed similarly occurs also in a coupled quantum wires device which is a quantum device using quantum wires in lieu of quantum boxes.